Revolutionary advances in genome research and the ability to create genetically specific strains of mice have resulted in an exponential increase in the number of mouse strains available for biomedical research. These newly created strains, particularly those in which the strain or mutation can be maintained by haploid germplasm, are most efficiently preserved by freezing and storing sperm. The methods currently employed for cryopreservation of mouse sperm display variably moderate success, are dependent on the genetic constitution of the male and have, thus, in general, been deemed inadequate for the safe preservation of most inbred mouse strains. Additional methods for cryopreservation of sperm, which are less adversely affected by genetic background, are needed.